Gallo S, McDermid JM, Al-Nimr RI, et al. - In this systematic review and meta-analysis of eligible randomized clinical trials, researchers explored the connections between maternal vitamin D supplementation, maternal 25-hydroxyvitamin D (25(OH)D) concentrations, and health outcomes. To identify studies that examined the health effects of vitamin D supplementation during pregnancy on maternal and infant health outcomes published from 2000 to 2016, a PubMed literature search was carried out. Findings suggested that supplementation with vitamin D during pregnancy improves maternal and infant 25(OH)D concentrations and can play a role in maternal insulin resistance and fetal growth. To further inform practices and policies on the amount of vitamin D that supports a healthy pregnancy, randomized clinical trials of high-quality dose-response assessing pregnancy-specific 25(OH)D thresholds and appropriate clinical outcomes are necessary.